DESCRIPTION: (Applicant's Abstract) We consider attention to be a construct which includes three interrelated classes of dynamic precesses: 1) those involved in redirecting attention, 2) those which selectively process information according to the focus of attention, and 3) those which are involved in sustaining the focus of attention. Due to the dynamic nature of these processes, investigation of the underlying brain mechanisms requires analyses of the active brain regions and their temporal activation patterns. Through our progress in the preceding grant period and through collaborative projects, we have the ability to acquire electroencephalography (EEG), magnetoencephalography (MEG), brain anatomical magnetic resonance images (MRI) and functional MRI (fMRI); as well as the capability to integrate and analyze these multi-modal data in our laboratory. This has enabled us to improve our methods for electromagnetic source estimation (EMSE) of the brain sources of EEG and MEG, including characterization of the temporal activation patterns in these brain areas. We now have the ability to constrain the EMSE with anatomical MRI and to inform the locations of likely brain sources with fMRI data in the same subjects. fMRI also serves as a stand-alone functional neuroimaging method for exploring the brain systems involved in attention. The proposed project applies this integrated multidisciplinary approach to examination of the spatial distribution of brain areas involved in these attentional processes and characterization of the temporal dynamics of the brain systems involved.